This proposal aims at elucidating functional and structural relationships between the retinal pigment epithelium (RPE) and photoreceptors which are necessary to the viability of the photoreceptors and are relevant to ocular disease. We will study adhesion between retina and RPE by separating the layers under a variety of experimental conditions, while monitoring the forces involved and the histologic consequences. We will study fluid transport across the RPE and the control of subretinal fluid volume by making experimental non-rhegmatogenous detachments in the living eye and correlating physiologic, fluorophotometric, histological, and electrophysiological data. We will also assess the importance of RPE-photoreceptor interactions by studying adhesion, transport and electrophysiology after removal of the photoreceptor outer segments by hemicholinium or tunicamycin. Our primary experimental animal for baseline studies will be the rabbit. Cats and monkeys will be used as more definitive models for the human eye. These experiments are relevant to a variety of human diseases in which the retina separates, subretinal fluid accumulates and visual function is lost. These studies may help suggest medical means of modifying subretinal fluid movement and retinal adhesion, to prevent and treat clinical detachments, and may help us to better understand retinal dystrophies and senile conditions which involve cellular loss at the level of the subretinal space.